Question

我有很多关联对象关系。关联对象具有用于时间戳记的额外字段。想法是仅在关联的时间戳在特定时间范围内时才返回关联的关系。

models.py

from rvt import db
from sqlalchemy_utils import IPAddressType


class ReportAssociation(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    entity_id = db.Column(db.Integer, db.ForeignKey('entity.id'))
    report_id = db.Column(db.Integer, db.ForeignKey('report_map.id'))
    timestamp = db.Column(db.DateTime)
    report_map = db.relationship('ReportMap', back_populates='entities')
    entity = db.relationship('Entity', back_populates='report_maps')
    __table_args__ = (
        db.UniqueConstraint('entity_id', 'report_id', 'timestamp'),
    )

    def __repr__(self):
        return f'ReportAssociation: {self.entity} {self.report_map} - {self.timestamp}'

class Entity(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    ip_address = db.Column(IPAddressType, unique=True, nullable=False)
    hostname = db.Column(db.String(64), index=True, nullable=True)
    region = db.Column(db.String(32), index=True, nullable=True)
    geo = db.Column(db.String(32), index=True, nullable=True)
    city = db.Column(db.String(32), index=True, nullable=True)
    asn = db.Column(db.String(8), index=True, nullable=True)
    subnet_desc = db.Column(db.String(256), index=True, nullable=True)
    report_maps = db.relationship('ReportAssociation', back_populates='entity', lazy="dynamic")
    timestamp = db.Column(db.DateTime)

    def __repr__(self):
        return f'<Entity {self.ip_address}>'

class ReportMap(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    pattern = db.Column(db.String(64), nullable=False, unique=True)
    name = db.Column(db.String(32), nullable=False, unique=True)
    short_name = db.Column(db.String(32), nullable=False, unique=True)
    wiki_url = db.Column(db.String(128), nullable=True, unique=False)
    entities = db.relationship('ReportAssociation', back_populates='report_map', lazy="dynamic")

    def __repr__(self):
        return f'<ReportMap {self.name}>'

我遇到的问题与查询有关。以下作品。

>>> e = Entity.query.one()
>>> e
<Entity 101.98.10.156>

>>> for i in e.report_maps.all():
...     print(i.timestamp)
...
2019-04-02 21:15:49.985126
2019-04-02 21:15:59.028121

>>> for i in e.report_maps.filter_by(timestamp='2019-04-02 21:15:59.028121'):
...     print(i.timestamp)
...
2019-04-02 21:15:59.028121

当我尝试使用以下内容时出现问题

>>> for i in e.report_maps.filter(timestamp < '2019-04-02 21:15:59.028121'):
...     print(i.timestamp)
...
Traceback (most recent call last):
  File "<console>", line 1, in <module>
NameError: name 'timestamp' is not defined

任何帮助将不胜感激。谢谢

Answer 1

使用过滤器方法时，必须使用ClassName.attribue，这样才能使用上一个查询，如下所示：

e.report_maps.filter(Entity.timestamp < '2019-04-02 21:15:59.028121').all()

多对多-基于额外关联字段的关联对象查询

1 个答案: